Ink jet printing devices that are known have arrangements in which, for example, printing ink is conveyed from a liquid reservoir to a movable printing head by means of comparatively long flexible hoses. It is quite difficult to replace the long hoses with a liquid reservoir that follows the movement of the printing head because the reservoir is subject to considerable acceleration and deceleration due to the rather rapid movements of the printing head. Consequently, the rapid movements of the liquid in the reservoir cause liquid agitation so that on one hand air is mixed into the liquid and on the other hand the liquid can leak out of the air inlet opening to the reservoir. Moreover, the air mixed with the liquid in the reservoir further causes foam to be formed on the liquid surface which, in turn, causes liquid to leak through the air inlet opening.